Work backwards from required-on-site to find latest enquiry, order, and approval dates.
Add a row per procured item for a full schedule. The critical-path item is flagged automatically.
Tender and programme tool. Always confirm with supplier lead times and your approval process.
For design guidance only. Always verify with procurement and the project programme.
About this procurement lead time calculator
This free procurement lead time calculator works backwards from a required-on-site date to find the latest enquiry, order, approval and dispatch dates for each procured item. It is built for UK building-services engineers, quantity surveyors and contractors pricing tenders or managing a project programme, where long-lead items such as switchboards, AHUs and chillers have to be ordered in time to land on site. Add a row per item and the critical-path item, the one needing the earliest order. Is flagged automatically.
How it works
For each item the calculator steps back from the required-on-site date through your programme float, then delivery (days), fabrication (weeks), approvals (weeks) and the shared internal order process and enquiry/quote turnaround (days), to give the latest enquiry, order (PO), approval-due and dispatch dates. With an approval gate, fabrication cannot start until approval is returned, so the chains run in series; in parallel mode approvals and fabrication overlap and the order date takes the more restrictive path, a backward-pass critical-path approach consistent with the CIOB Code of Practice for Programme Management referenced in the tool. Dates can be counted as calendar days or working days, where working-day mode skips weekends and a bundled list of England & Wales bank holidays from gov.uk. It is an indicative programming tool, not a substitute for confirmed supplier lead times.
Frequently asked questions
What is the difference between an approval gate and parallel mode?
With an approval gate, fabrication only begins once approval is returned, so approvals and fabrication run one after the other. In parallel mode they may overlap, and the order date is set by whichever path, fabrication or approvals. Is more restrictive. If approvals drive the order earlier than fabrication needs, the tool flags an approval-led programme.
Does it account for weekends and bank holidays?
Yes, if you choose working-day mode. It then counts only Monday to Friday and skips a bundled list of England & Wales bank holidays sourced from gov.uk. Calendar-day mode counts every day. The bank-holiday list is fixed in the tool and should be updated each year.
Can I confirm orders straight from these dates?
No. Treat the output as an indicative programming and tender aid. Always confirm supplier lead times, factory shutdowns and logistics constraints, and verify against your procurement and project programme before placing orders.